In a manufacturing plant with a job-shop type production system (for example, a semiconductor device manufacturing plant or an organic EL device manufacturing plant), production is controlled by an MES (Manufacturing Execution System). In such a manufacturing plant, a manufacturing process system is utilized, which includes a plurality of processing devices for processing workpieces, a transfer device for transferring the workpieces to each processing device, a transfer control device for controlling an operation of the transfer device, and a MES for determining a processing device to process the workpieces, informing the transfer control device of a transfer destination of the workpieces and informing the processing device of the procedure for processing the workpieces.
Software may be used which includes a procedure of communicating with a plurality of processing devices processing workpieces, a procedure of communicating with a transfer device transferring the workpieces between processing devices, and a procedure of communicating with a manufacturing instruction device instructing the processing devices to process the workpieces.
A plant MES and a MCS (Material Control System) may be used to control an OHT (Overhead Hoist Transport) based on various instructions received from the MES, share information such as plant layouts and so on, in order to achieve an efficient transfer.
A process management system may be used which allows the processing device to process another workpiece if the time until a workpiece to be preferentially processed arrives at a processing device is sufficiently long and that if the time until the workpiece to be preferentially processed arrives at the processing device is short, the processing device waits for the arrival of the workpiece to be preferentially processed.
A power supply system may be used in which the arrival time needed for an arrival of a workpiece to be processed is compared to a drive time of the processing device in a power saving state. If the arrival time is longer than the drive time, the processing device remains in the power saving mode.
In addition, there is known a manufacturing system in which, if a processing device in a ready state (a standby state) does not receive a specified processing instruction from a host computer for a certain period of time, the processing device switches from the ready state to an idle state (a dormant state), in order to reduce the amount of energy consumption.
Some semiconductor manufacturing plants have a plurality of processing devices performing different processes for workpieces. These processing devices are in an idle state while no process is performed for the workpieces. Here, the idle state refers to a state where some degree of energy continues to be consumed to allow the processing devices to return to an operation state quickly, although energy consumption in this state is less than that in a normal operation state. This energy consumption in the idle state is wasteful energy which has no contribution to semiconductor device manufacturing. In fact, as the number of processing devices increases, more wasteful energy is consumed.
For example, there is a technique for achieving energy saving by automatically transitioning a processing device from a normal state to an idle state if the waiting time of the processing device exceeds a predetermined period of time. However, in this proposed technique, although each processing device may be set to the idle state, it is not easy to save energy consumed in the entire semiconductor manufacturing plant since the idle state itself consumes wasteful energy, as described above.
Energy is not the only wasteful consumption in semiconductor manufacturing plants. In general, processing devices are required to keep environmental conditions, such as temperature, humidity, a degree of vacuum, a supply or discharge gas flow rate and so on within a chamber, constant in order to process workpieces within the chamber. Once the environmental conditions are greatly varied, it may take some time to return the processing devices to the original environmental conditions. Therefore, in the idle state the environmental conditions are not extremely varied, and accordingly, the resources and costs required for maintaining the environmental conditions are continually consumed wastefully.
From this background, a technique has been developed for switching the operation mode while considering recovery time required for a processing device switching the operation mode. In addition, different types of energy saving modes having different amounts of energy consumption are provided to achieve energy saving as much as possible within a range not affecting the processing by the processing devices.
An operation mode switching can be performed in consideration of the recovery time for switching of the operation mode of the processing device. However, if the operation mode is necessarily switched when the standby time of the processing device is longer than the recovery time, the operation mode may be frequently switched, which is likely to impose a burden on a power supply and so on of the processing device. In addition, in some cases, workpieces may require high precision for processing the quality of film thickness, film quality and so on. In this case, even if the standby time is longer than the recovery time, it is preferable not to switch the operation mode.
Although the switching of the operation mode is performed based on a balance with the recovery time, there is no know technique on switching of the operation mode under specified conditions other than recovery time. Thus, there is no guarantee that there will be optimal switching of the operation mode.
In addition, although the switching of the operation mode of the processing device based on the balance with the transfer timing is known, there is no known technique which considers switching of the operation mode based on the length of the standby time of the processing device.
In addition, it is known that when a predetermined time elapses from a state where the processing device is set to the normal mode, the normal mode is automatically transitioned to the energy saving mode. This transition means that the processing device is operated in the normal mode until the predetermined time elapses, i.e., meaning wasteful power consumption for at least this period.
Although various ways to achieve energy saving as described above are known, there is room for reduction of energy consumption. In addition, no way has been proposed to achieve optimal energy saving associated with certain types of workpieces.
In many cases, from the standpoint of consumption of mass energy, semiconductor manufacturing plants may make special contracts related to limitations on energy use with power companies. In such types of contracts, a level of the maximal energy consumption in the semiconductor manufacturing plants is set and the use of energy is permitted only within a range which does not exceed this level.
However, in the prior art, there exists no proper structure for scheduling a plurality of processing devices to consume the optimal amount of energy within a range of maximum energy consumption. As a result, there is a possibility to use less energy with a margin, or conversely, there may be some instability in the energy supplied from power companies due to the excessive level of maximal energy consumption.
In addition, in conventional systems, it takes some time for a processing device to be switched from a ready state to an idle state. Since an equipment associated with the processing device is switched from a ready state to an idle state after the processing device is set to the idle state, the equipment takes more time to be switched to the idle state. Thus, it becomes difficult to reduce energy consumption in the equipment.